Production of battery grade materials via an oxalate method

ABSTRACT

An active electrode material for electrochemical devices such as lithium ion batteries includes a lithium transition metal oxide which is free of sodium and sulfur contaminants. The lithium transition metal oxide is prepared by calcining a mixture of a lithium precursor and a transition metal oxalate. Electrochemical devices use such active electrodes.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional application of U.S. patentapplication Ser. No. 13/099,756, filed on May 3, 2011, incorporatedherein by reference in its entirety.

GOVERNMENT RIGHTS

The United States Government has rights in this invention pursuant toContract No. DE-AC02-06CH11357 between the United States Department ofEnergy and the UChicago Argonne, LLC representing Argonne NationalLaboratory.

FIELD

The technology relates to active materials for use in electrochemicaldevices such as lithium-ion batteries, and the preparation of suchmaterials.

BACKGROUND

Since their first commercialization in the 1990s, rechargeablelithium-ion (Li-ion) batteries have served as major power sources for awide range of electronic products. An increase in global energy demand,rising and fluctuating crude oil prices, and environmental concerns inrecent years have led to an increase in demand for Li-ion batteries. Inparticular, Li-ion battery technology is being developed forapplications in electric vehicles (EVs), hybrid electric vehicles(HEVs), and plug-in hybrid electric vehicles (PHEVs). For suchapplications, improved Li-ion batteries providing high energy densityand high power capacity are required.

In general, the energy density of a Li-ion cell depends on the cathodematerial used in the cell. Typically, lithium transition metal oxidesare used as lithium-ion battery cathode materials. In general, themorphology of such lithiated metal oxides is dependant on the startingmetal precursors and the synthetic methods employed. Both of theseconsiderations also play an important role in controlling theelectrochemical properties of the cathode materials in Li-ion cells.

The most common industrial method for preparation of materials forLi-ion batteries is the hydroxide co-precipitation method. In thismethod, transition metal sulfates in aqueous solutions are reacted withsodium hydroxide solution under very corrosive alkaline conditions tofabricate transition metal hydroxides. The transition metal hydroxidesare used to synthesize the lithium transition oxide materials that areused as positive active materials in lithium ion cells. As analternative, a carbonate co-precipitation method may be used. Such amethod uses sodium carbonate to synthesize battery grade materials. Theadvantage of this method over the hydroxide method is the preservationof the oxidation states of transition metals in the +2 oxidation statein the prepared carbonate precursors. However, both the hydroxide andcarbonate co-precipitation methods may result in contamination of theprecursors during the formation of particles with contaminants such assodium and sulfur which are used in the precipitation processes. Thesespecies cannot be avoided even after extensive washing because they areprecipitated as sodium sulfate Na₂SO₄ during the co-precipitation of thetransition metal hydroxides and carbonates. The presence of suchimpurities in the electrode materials negatively impacts the performanceof the Li-ion cells.

SUMMARY

In one aspect, an active electrode material is provided including alithium transition metal oxide which is free of sodium and sulfurcontaminants. The lithium transition metal oxide may be prepared bycalcining a mixture of a lithium precursor and a transition metaloxalate. In some embodiments, the lithium transition metal oxidecomprises a compound of formula Li_(x)[M¹ _(α)M² _(β)M³ _(γ)]O_(z);where M¹, M², and M³ are transition metals; and where 0<x≦2; 0<α≦1;0<β≦1; 0<γ≦1; and 0<z≦3. In some embodiments, M¹ is Ni, Fe, Cu, Zn, Mg,Ca, Sr, or Ba; M² is Co, Cr, V, Y, La, Ce or Al; and M³ is Mn, Ti, Zr,Nb, Mo, or Ru. In some embodiments, M¹ is Ni; M² is Co; and M³ is Mn. Insome embodiments, 1<x≦2; 0<α≦0.33; 0<β≦0.5; 0<γ≦0.8; and 2<z≦3. In someembodiments, 1<x≦2; 0<α≦0.33; 0<β≦0.5; 0<γ≦0.8; and 2<z≦3; and the sumof α, β, and γ is 1. In some embodiments, 1<x≦2; 0<α≦0.33; β=0; 0<γ≦0.8;and 2<z≦3; and the sum of α and γ is 1.

In some embodiments, the lithium transition metal oxide exhibits acapacity of greater than 200 mAh/g when used as a positive electrode ina Li coin cell. In some embodiments, the lithium precursor includeslithium carbonate, lithium hydroxide, lithium nitrate, lithium acetate,lithium oxalate, lithium hydride, lithium oxide, lithium peroxide,lithium sulfate, or lithium fluoride. In some embodiments, thetransition metal oxalate includes a compound of formula [M¹ _(α′)M²_(β′)M³ _(γ′)]C₂O₄; where M¹, M², and M³ are transition metals; andwhere 0<α′≦1; 0<β′≦1; and 0<γ′≦1. In some embodiments, M¹ is Ni, Fe, Cu,Zn, Mg, Ca, Sr, or Ba; M² is Co, Cr, V, Y, La, Ce or Al; and M³ is Mn,Ti, Zr, Nb, Mo, or Ru. In some embodiments, M¹ is Ni; M² is Co; and M³is Mn. In some embodiments, 0<α′≦0.33; 0<β′≦0.5; and 0<γ′≦0.8. In someembodiments, 0<α′≦0.33; 0<β′≦0.5; and 0<γ′≦0.8; and the sum of α′, β′,and γ′ is 1. In some embodiments, 0<α′≦0.33; β′=0; and 0<γ′≦0.8 and thesum of α′ and γ′ is 1.

In one aspect, a method of preparing a lithium transition metal oxide isprovided including calcining a mixture of a lithium precursor and atransition metal oxalate. In some embodiments, the calcining isconducted at a temperature of from about 500° C. to about 1200° C. Insome embodiments, the calcining is conducted at a temperature of fromabout 700° C. to about 1000° C.

In another aspect, a method is provided which includes preparing thetransition metal oxalate by preparing a transition metal ion solutionand a solution of oxalic acid and a precipitating agent; and adding thetransition metal ion solution to the solution of the oxalic acid and theprecipitating agent to precipitate the transition metal oxalate. In someembodiments, the precipitating agent includes ammonium hydrogen oxalate,di-ammonium oxalate, oxalic acid, lithium oxalate, sodium oxalate,potassium oxalate.

In some embodiments, the transition metal oxalate includes a compound offormula [M¹ _(α′)M² _(β′)M³ _(γ′)]C₂O₄; where M¹, M², and M³ aretransition metals; and where 0<α′≦1; 0<β′≦1; and 0<γ′≦1. In someembodiments, the transition metal ion solution comprises metal ions ofNi, Co, Mn, Fe, Cr, V, Ti, Cu, Zn, Mo, W, Zr, Nb, Ru or a mixture of anytwo or more thereof.

In another aspect, an electrode is provided that includes a transitionmetal oxide prepared by calcination of a lithium precursor and atransition metal carbonate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the pH stability for(Ni_(1/3)Co_(1/3)Mn_(1/3))C₂O₄.2H₂O, according to Example 1.

FIG. 2 depicts a thermogravimetric analysis (TGA) and differentialthermal analysis of (Ni_(1/3)Co_(1/3)Mn_(1/3))C₂O₄.2H₂O, preparedaccording to Example 1.

FIG. 3 depicts the charge and discharge cycle during the first cycle ofthe Li_(1.1)(Ni_(1/3) Co_(1/3) Mn_(1/3))O₂ material used as the activecathode component in a Li/Li_(1.1)(Ni_(1/3)Co_(1/3) Mn_(1/3))O₂ cell,according to Example 5.

FIG. 4 depicts the charge and discharge capacity during the 16 cycles ofthe Li_(1.1)(Ni_(1/3) Co_(1/3) Mn_(1/3))O₂ material used as the activecathode component in a Li/Li_(1.1)(Ni_(1/3)Co_(1/3) Mn_(1/3))O₂ cell,according to Example 5.

FIG. 5 depicts the TGA graph of (Ni_(0.25)Mn_(0.75))C₂O₄.2H₂O, accordingto Example 6.

FIG. 6 is a graph of the specific capacity Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5) as a function of voltage, according to Example 7.

FIG. 7 is a graph comparing the cycling properties of Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.55) according to Example 7, and the same chemicalcomposition, prepared by the carbonate method.

DETAILED DESCRIPTION

In one aspect, an active electrode material is provided including alithium transition metal oxide which is free of sodium and sulfurcontaminants. Such metal oxides are prepared from oxalate precursorsthat eliminate the need for the use of contaminating materials,including, but not limited to Na₂SO₄.

Accordingly, an active electrode material is provided which can beproduced from a transition metal oxalate. In particular, the activeelectrode material is prepared by calcining a mixture of a lithiumprecursor and a transition metal oxalate. As used herein, “calcination”refers to thermal treatment of the mixture in an oxygen atmosphere.Typically, a material that is “calcined” is heated in a furnace, or likepiece of equipment, to a temperature in excess of 400° C. in an inertatmosphere, an air atmosphere, or an atmosphere containing oxygen. Thus,in some embodiments, the mixture is calcined by heating from about 400°C. to about 1,200° C., or 700° C. to about 1,000° C., in either an inertatmosphere or in the presence of oxygen such as in air.

Lithium precursors suitable for use in the active electrode may includelithium salts such as, but not limited to, lithium carbonate, lithiumhydroxide, lithium nitrate, lithium acetate, lithium oxalate, lithiumhydride, lithium oxide, lithium peroxide, lithium sulfate, or lithiumfluoride (Revised) or a mixture of any two or more thereof.

Transition metal oxalates suitable for use in the active electrode mayinclude transition metals such as Ni, Co, Mn, Fe, Cr, V, Ti, Cu, Zn, Mo,W, Zr, Nb, Ru, or a mixture of any two or more thereof. For example, thetransition metal oxalate may be an oxalate of any of the above metalssingly or a mixture of oxalates of any two or more of the above metals.Where the transition metal oxalate is a mixture of oxalates, the ratiobetween the transition metals is based on the desired crystallinestructure and electrochemical performances. In some embodiments, thetransition metal oxalate may include waters of hydration.

In some embodiments, the lithium transition metal oxide includes acompound of formula Li_(x)[M¹ _(α)M² _(β)M³ _(γ)]O_(z); where M¹, M²,and M³ are transition metals; and where 0<x≦2; 0<α≦1; 0<β≦1; 0<γ≦1; and0<z≦3. In some embodiments, M¹ is Ni, Fe, Cu, Zn, Mg, Ca, Sr, or Ba; M²is Co, Cr, V, Y, La, Ce or Al; and M³ is Mn, Ti, Zr, Nb, Mo, or Ru. Insome embodiments, M¹ is Ni; M² is Co; and M³ is Mn. In some embodiments,0<x≦2; 0<α≦0.33; 0<β≦0.5; 0<γ≦0.8; and 2<z≦3. In some embodiments,1<x≦2; 0<α≦0.33; 0<β≦0.5; 0<γ≦0.8; and 2<z≦3; and the sum of α, β, and γis 1. In some embodiments, 1<x≦2; 0<α≦0.33; β=0; 0<γ≦0.8; and 2<z≦3; andthe sum of α and γ is 1. It is understood that the transition metaloxides may be in hydrated form.

The lithium transition metal oxides are prepared from the correspondingoxalates. Accordingly, in some embodiments, the transition metal oxalateincludes a compound of formula formula [M¹ _(α′)M² _(β′)M³ _(γ′)]C₂O₄;where M¹, M², and M³ are transition metals; and where 0<α′≦1; 0<β′≦1;and 0<γ′≦1. In some embodiments, M¹ is Ni, Fe, Cu, Zn, Mg, Ca, Sr, orBa; M² is Co, Cr, V, Y, La, Ce or Al; and M³ is Mn, Ti, Zr, Nb, Mo, orRu. In some embodiments, M¹ is Ni; M² is Co; and M³ is Mn. In someembodiments, 0<α′≦0.33; 0<β′≦0.5; and 0<γ′≦0.8. In some embodiments,0<α′≦0.33; 0<β′≦0.5; and 0<γ′≦0.8; and the sum of α′, β′, and γ′ is 1.In some embodiments, 0<α′≦0.33; β′=0; and 0<γ′≦0.8; and the sum of α′and γ′ is 1. It is understood that the transition metal oxides may be inhydrated form.

Such transition metal oxides have enhanced capacity as compared to thesame transition metal oxide prepared by using the hydroxide or carbonatemethods. In some embodiments, the lithium transition metal oxideexhibits a capacity greater than 200 mA/g when it is used as a positiveelectrode in Li coin cell.

In one aspect, a method is provided for preparing a lithium transitionmetal oxide for use as an active electrode material. The method includescalcining a mixture of a lithium precursor and a transition metaloxalate. The mixture may be calcined by heating at about 400° C. toabout 1,200° C. In other embodiments, the mixture is calcined from about700° C. to about 1,000° C. As noted, the calcination may be carried outin either an inert atmosphere or in the presence of oxygen. For example,the calcination may be carried out in a gas typically considered to beinert such as, but not limited to, nitrogen, helium, neon, or argon. Thecalcination may also be carried out in pure oxygen, air, or in a mixturewith other gases such as carbon dioxide, nitrogen, helium, neon, argon,or a mixture of any two or more such gases.

The transition metal oxalate(s) may be prepared by preparing atransition metal ion solution and a solution of oxalic acid and aprecipitating agent; and adding the transition metal ion solution to thesolution of the oxalic acid and the precipitating agent to precipitatethe transition metal oxalate. The transition metal ion solution isprepared from metal salts of the transition metals. Accordingly, thetransition metal salts include sulfate, nitrate, acetate, or phosphateof one or more of Ni, Co, Mn, Fe, Cr, V, Ti, Cu, Zn, Mo, W, Zr, Nb, orRu. Depending on the desired metal composition in the lithium transitionmetal oxide, aqueous solutions of metal salts of different metals can beadded to form a transition metal ion solution. In some embodiments, theconcentration of the metal ions in the combined metal salt solution isfrom about 0.1M to about 3M. In other embodiments, the concentration ofthe metal ions in the combined metal salt solution is from about 0.5M toabout 2M. In other embodiments, the concentration of the metal ions inthe combined metal salt solution is about 1M.

As noted above, the precipitation may be carried out in the presence ofa precipitating agent. Suitable precipitating agents include, but arenot limited to, ammonium hydrogen oxalate, di-ammonium oxalate, oxalicacid, lithium oxalate, sodium oxalate, potassium oxalate, or mixturethereof. In some embodiments, the concentration of the precipitatingagent is from about 0.5M to about 1M in the original solution ofprecipitating agent. In other embodiments, the concentration of theprecipitating agent is less than 0.5M. In yet other embodiments, theconcentration of the precipitating agent is greater than 1 M.

In some embodiments, the concentration of the oxalic acid is from about0.1M to about 2M in the original solution of oxalic acid. In someembodiments, the concentration of the oxalic acid is about 1M.

The pH of the solution may be monitored and adjusted duringprecipitation such that it remains constant or at a target pH. In oneembodiment, the target pH is between 2 and 8. In other embodiments, thetarget pH is between 3 and 5. In other embodiments, the temperature ofthe precipitation is about 30° C. to about 100° C. In yet otherembodiments, the temperature of the precipitation is about 50° C. toabout 80° C. In some other embodiments, the temperature of theprecipitation is about 70° C.

In some embodiments, the transition metal oxalates that precipitateinclude particles of different shapes including irregular shapes. Insome embodiments, the particles have various shapes includingapproximately diamond, spherical, needle or planar shapes. Particleswith diamond shape, as understood by those skilled in the art, are 3Dparticles roughly shaped like a cube with six or more faces. These outersurface of the particles are characterized by straight edges. Use of theterm “diamond” does not mean that every particle is a perfect diamond,merely that a majority of the particles have a general diamond shape atthe micron level. In some embodiments, the particles have an averagesize from about 0.1 μm to 100 μm. In some embodiments, the particleshave a size between 5 and 20 μm.

In another aspect, an electrode is provided including a lithiumtransition metal oxide which is prepared from a transition metaloxalate. In some embodiments, the electrodes are cathodes and/or anodesfor use in an electrochemical device. In one embodiment, the electrodeis a cathode. In some embodiments, the lithiated transition metal oxidedescribed herein may be blended or mixed with lithium transition metaloxide produced by other methods. Other lithium transition metal oxidesrefers to same or similar compositions that are made using anothermethod such as the hydroxide or carbonate methods. Depending on themethod of preparation, the same lithiated transition metal oxide mayhave different properties when used as an electroactive material in anelectrochemical cell. By blending lithiated transition metal oxides madeusing different methods, electroactive materials with unique propertiescan be prepared. In some embodiments, blending lithiated transitionmetal oxides prepared from a transition metal oxalate with otherlithiated transition metal oxides prepared from a transition metalhydroxide or carbonate or both, may be used to increase the energy andpower densities of the lithiated transition metal oxide mixtures.

The electrodes described above may be used in a wide variety ofelectrochemical devices. Such devices may include, but are not limitedto batteries and capacitors. Such devices may include a cathodeincluding the transition metal oxide as prepared from the transitionmetal oxalate; an anode; and a non-aqueous electrolyte. The anode insuch devices may include, but is not limited to, graphite, amorphouscarbon, Li₄Ti₅O₁₂, tin alloys, silicon alloys, intermetallic compounds,lithium metal, or mixtures of any two or more thereof. Suitable graphitematerials may include, but are not limited to, natural graphite, hardcarbon, soft carbon, petroleum coke, artificial graphite, graphitizedmeso-carbon microbeads, graphite fibers, graphene, graphene oxide,carbon nanotubes, or amorphous carbon materials.

The non-aqueous electrolyte may be any conventional or otherwisesuitable organic electrolyte known in the art and includes a polaraprotic solvent and a salt. A variety of solvents may be employed in theelectrolyte as the polar aprotic solvent. Some illustrative polaraprotic solvents include liquids and gels capable of solubilizingsufficient quantities of the lithium salt and the redox shuttle so thata suitable quantity of charge can be transported from the positiveelectrode to negative electrode. The solvents can be used over a widetemperature range, e.g., from −30° C. to 70° C. without freezing orboiling, and are stable in the electrochemical range within which thecell electrodes and shuttle operate. Suitable solvents include, but arenot limited to, dimethyl carbonate; ethyl methyl carbonate; diethylcarbonate; methyl propyl carbonate; ethyl propyl carbonate; dipropylcarbonate; bis(trifluoroethyl) carbonate; bis(pentafluoropropyl)carbonate; trifluoroethyl methyl carbonate; pentafluoroethyl methylcarbonate; heptafluoropropyl methyl carbonate; perfluorobutyl methylcarbonate; trifluoroethyl ethyl carbonate; pentafluoroethyl ethylcarbonate; heptafluoropropyl ethyl carbonate; perfluorobutyl ethylcarbonate; fluorinated oligomers; dimethoxyethane; triglyme;dimethylvinylene carbonate; tetraethyleneglycol; dimethyl ether;polyethylene glycols; sulfones; and γ-butyrolactone.

Suitable salts that may be used in the electrolytes, include, but arenot limited to, Li[B(C₂O₄)₂]; Li[BF₂(C₂O₄)]; LiClO₄; LiBF₄; LiAsF₆;LiSbF₆; LiBr, LiPF₆; Li[CF₃SO₃]; Li[N(CF₃SO₂)₂]; Li[C(CF₃SO₂)₃];Li[B(C₆F₅)₄]; Li[B(C₆H₅)₄]; Li[N(SO₂CF₃)₂]; Li[N(SO₂CF₂CF₃)₂];LiN(SO₂C₂F₅)₂; Li[BF₃C₂F₅]; and Li[PF₃(CF₂CF₃)₃]; and lithium alkylfluorophosphates.

All publications, patent applications, issued patents, and otherdocuments referred to in this specification are herein incorporated byreference as if each individual publication, patent application, issuedpatent, or other document was specifically and individually indicated tobe incorporated by reference in its entirety. Definitions that arecontained in text incorporated by reference are excluded to the extentthat they contradict definitions in this disclosure.

The present technology, thus generally described, will be understoodmore readily by reference to the following examples, which are providedby way of illustration and are not intended to be limiting.

EXAMPLES Example 1

Preparation of Ni_(1/3)Co_(1/3)Mn_(1/3)C₂O₄.2H₂O. In a first vessel,nickel sulfate hydrate, cobalt sulfate hydrate, and manganese sulfatehydrate were dissolved in water, with stirring, to prepare a 1 Msolution of Ni, Co, and Mn ions in a 1:1:1 ratio. In other words, thesolution contains 0.33M Ni, 0.33 M Co, and 0.33M Mn. In second vessel,oxalic acid was dissolved in water, with stirring, to prepare a 1 Maqueous solution. In a third vessel, ammonium hydrogen oxalate wasdissolved in water, with stirring, to prepare a 1 M solution. The oxalicacid solution was then added to the ammonium hydrogen oxalate solution,with stirring.

The metal solution in the first vessel was then added dropwise to themixture of the oxalic acid and oxalate, until precipitation of metaloxalate particles was observed. The pH of the oxalic acid/oxalatesolution was monitored during addition of the transition metal solution.FIG. 1 is a graph of the pH change of the oxalic acid/oxalate solutionas a function of the volume of addition. Initially, the pH of thesolution was 2.5 and no precipitation occurred. At about pH 2.2precipitation began. The addition of metal solution continuedthereafter. Throughout the addition of the metal solution, thetemperature of the solutions was held constant at 70° C.

The precipitate was then collected by filtration, washed with water, anddried at 100° C. SEM images of the Ni_(1/3)Co_(1/3)Mn_(1/3)C₂O₄.2H₂Owere obtained. The images show large, clear cut and dense particleshaving a cuboid shape with dimensions of about 10 μm on a side. An XRD(x-ray diffraction) pattern of the particles was recorded and found toexhibit similar peaks as that of FeC₂O₄.2H₂O.

The Ni_(1/3)Co_(1/3)Mn_(1/3)C₂O₄.2H₂O was analyzed by TGA (thermalgravimetric analysis). FIG. 2 is a graph of the TGA from roomtemperature to 500° C. The first weight loss, observed between 150 and225° C., is attributed to the loss of the waters of hydration. Thesecond major loss, observed between 225 and 325° C. is attributed to theloss of the oxalic group (C₂O₄ ²). The 57% weight loss is consistentwith the chemical formula of Ni_(1/3)Co_(1/3)Mn_(1/3)C₂O₄.2H₂O. The lossof water from Ni_(1/3)Co_(1/3)Mn_(1/3)C₂O₄.2H₂O is an endothermicphenomenon, whereas the loss of the oxalic group is an exothermicphenomenon.

After the TGA, an XRD of the material that remained after heating at500° C. revealed that it had a similar pattern to that of NiMn₂O₄,confirming that upon heating the Ni_(1/3)Co_(1/3)Mn_(1/3)C₂O₄.2H₂Odecomposes to NiCoMnO₄, having a spinal-like structure. SEM images ofthe NiCoMnO₄ were recorded, and illustrate parallel layers of highlyordered nano-particulates of less than about 100 nm.

Example 2

Preparation of LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂. Lithium carbonate was addedto the particles of Ni_(1/3)Co_(1/3)Mn_(1/3)C₂O₄.2H₂O at a ratio ofLi:Ni:Co:Mn of 1:0.33:0.33:0.33, and the materials were mixed in a drymixer. This mixture was then calcined at 900° C. for 12 hours to yieldLiNi_(1/3)Co_(1/3)Mn_(1/3)O₂.

Example 3

Preparation of Li_(1.1)Ni_(1/3)Co_(1/3)Mn_(1/3)O₂. The same procedure ofExample 2 was followed, but with a ratio of Li:Ni:Co:Mn of1.1:0.33:0.33:0.33.

SEM images of the Li_(1.1)Ni_(1/3)Co_(1/3)Mn_(1/3)O₂ were recorded. Theimages show micro-porous particles having nano-pores. Bothcharacteristics are unique to the oxalate precursor due to the removalof water and oxalic groups occur as the temperature of the reactionincreases.

Example 4

Preparation of Li_(1.15)Ni_(1/3)Co_(1/3)Mn_(1/3)O₂. The same procedureof Example 2 was followed, but with a ratio of Li:Ni:Co:Mn of1.15:0.33:0.33:0.33.

Example 5

Coin cell. The performance of the Li_(1.1)(Ni_(1/3)Co_(1/3)Mn_(1/3))O₂was tested in a coin-cell battery. A positive electrode was made bycoating a paste of 80 wt % of Li_(1.1)(Ni_(1/3)Co_(1/3)Mn_(1/3))O₂, 10wt % of acetylene black carbon as a conducting additive, and 10 wt %polyvinylidene fluoride (PVDF) binder on an aluminum foil. Coin-cells(CR2031) were assembled inside a glove box using the positive electrode,and a lithium metal counter electrode. An electrolyte of 1.2 M LiPF₆ in(EC:PC:DMC) (1:1:3 wt %) was used. The cells were charged to 4.3 V andthe charge/discharge capacity was monitored. FIG. 3 depicts the firstcharge and discharge profile curve ofLi_(1.1)(Ni_(1/3)Co_(1/3)Mn_(1/3))O₂. The discharge capacity after 12hours (C/12) of discharge was 158 mAh/g. FIG. 4 depicts the capacity ofthe coin cell after 16 cycles under C/12, and shows that the capacitywas retained over the cycles indicating that the performance is stableand efficient.

Example 6

Preparation of Ni_(0.25)Mn_(0.75)C₂O₄.2H₂O. In a first vessel, nickelsulfate hydrate and manganese sulfate hydrate were dissolved in water toprepare a 1 M aqueous transition metal solution with a ratio of Ni to Mnof 1:3 on a mol basis. This metal solution was then added to a secondvessel containing oxalic acid at a constant temperature of 70° C., toform a metal oxalate precipitate. The precipitateNi_(0.25)Mn_(0.75)C₂O₄.2H₂O was collected by filtration, washed severaltimes with water, and dried at 100° C. for several hours. FIG. 5 is aTGA curve of Ni_(0.25)Mn_(0.75)C₂O₄.2H₂O. The first step in the curvecorresponds to the removal of water (20% weight loss), and the secondstep corresponds to the removal of CO₂ (additional 40% weight loss). Theweight loss confirms the chemical composition ofNi_(0.25)Mn_(0.75)C₂O₄.2H₂O. The complete decomposition of this oxalatecompound occurs at 400° C., which is significantly lower than thetemperature required conversion of a carbonate precursor to a metaloxide. In the carbonate method, temperature of 600° C., or more, arerequired.

Example 7

Preparation of LiNi_(0.25)Mn_(0.75)O₂. Lithium carbonate was added tothe particles of Ni_(0.25)Mn_(0.75)C₂O₄.2H₂O at a ratio of Li:Ni:Mn of1:0.25:0.75, and the materials were mixed in a dry mixer. This mixturewas then calcined at 900° C. for 12 hours to yieldLiNi_(0.25)Mn_(0.75)O₂. An SEM image ofLi_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5) was recorded and shows submicron,aligned primary particles suitable for facile lithium extraction andinsertion and high rate capability battery applications.

FIG. 6 is a graph of the specific capacity Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5) as a function of voltage. The capacity of the materialis 224 mAh/g when charged between 2 and 4.6 V

FIG. 7 is a comparison of the cycling properties ofLi_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5) (a), with the same chemicalcomposition prepared by mixing Ni_(0.25)Mn_(0.75)Co₃ carbonate andlithium carbonate Li₂Co₃ and firing the mixture at 900° C. for 15 hours(b). The two materials were tested as the active cathode component in aLi/Li_(1.1)(Ni_(1/3)Co_(1/3) Mn_(1/3))O₂ cell. When both materials arecharged to 4.6 V and discharged to 2V for several cycles, the materialprepared via the transition metals oxalate source (a) showed a capacityof 224 mAh/g versus a capacity of only 183 mAh/g that the material madevia the transition metal carbonate source.

While some embodiments have been illustrated and described, it should beunderstood that changes and modifications can be made therein inaccordance with ordinary skill in the art without departing from theinvention in its broader aspects as defined in the following claims.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the elements (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Additionally, the terms andexpressions employed herein have been used as terms of description andnot of limitation, and there is no intention in the use of such termsand expressions of excluding any equivalents of the features shown anddescribed or portions thereof, but it is recognized that variousmodifications are possible within the scope of the invention claimed.Additionally the phrase “consisting essentially of” will be understoodto include those elements specifically recited and those additionalelements that do not materially affect the basic and novelcharacteristics of the claimed invention. The phrase “consisting of”excludes any element not specifically specified.

The present disclosure is not to be limited in terms of the particularembodiments described in this application. Many modifications andvariations can be made without departing from its spirit and scope, aswill be apparent to those skilled in the art. Functionally equivalentmethods and apparatuses within the scope of the disclosure, in additionto those enumerated herein, will be apparent to those skilled in the artfrom the foregoing descriptions. Such modifications and variations areintended to fall within the scope of the appended claims. The presentdisclosure is to be limited only by the terms of the appended claims,along with the full scope of equivalents to which such claims areentitled. It is to be understood that this disclosure is not limited toparticular methods, reagents, compounds compositions or biologicalsystems, which can, of course, vary. It is also to be understood thatthe terminology used herein is for the purpose of describing particularembodiments only, and is not intended to be limiting.

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, particularly in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” “greater than,” “less than,” and the likeinclude the number recited and refer to ranges which can be subsequentlybroken down into subranges as discussed above. Finally, as will beunderstood by one skilled in the art, a range includes each individualmember.

As used herein, “about” will be understood by persons of ordinary skillin the art and will vary to some extent depending upon the context inwhich it is used. If there are uses of the term which are not clear topersons of ordinary skill in the art, given the context in which it isused, “about” will mean up to, plus or minus 10% of the particular term.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

What is claimed is:
 1. An active electrode material comprising: alithium transition metal oxide prepared by calcining a mixture of alithium precursor and a transition metal oxalate.
 2. The activeelectrode material of claim 1, wherein: the lithium transition metaloxide comprises a compound of formulaLi_(x)[M¹ _(α)M² _(β)M³ _(γ)]O_(z); M¹, M², and M³ are transitionmetals; and 0<x≦2; 0<α≦1; 0<β≦1; 0<γ≦1; and 0<z≦3.
 3. The activeelectrode material of claim 2, wherein the transition metal ionscomprise at least three of Ni, Co, Mn, Fe, Cr, V, Ti, Cu, Zn, Mo, W, Zr,Nb, or Ru.
 4. The active electrode material of claim 2, wherein M¹ isNi, Fe, Cu, Zn, Mg, Ca, Sr, or Ba; M² is Co, Cr, V, Y, La, Ce or Al; andM³ is Mn, Ti, Zr, Nb, Mo, or Ru.
 5. The active electrode material ofclaim 2, wherein M¹ is Ni; M² is Co; and M³ is Mn.
 6. The activeelectrode material of claim 2, wherein 1<x≦2; 0<α≦0.33; 0<β≦0.5;0<γ≦0.8; and 2<z≦3; and the sum of α, β, and γ is
 1. 7. The activeelectrode material of claim 2, wherein 1<x≦2; 0<α≦0.33; β=0; 0<γ≦0.8;and 2<z≦3; and the sum of α and β is
 1. 8. The active electrode materialof claim 1, wherein the lithium transition metal oxide exhibits acapacity of greater than 200 mAh/g when used as a positive electrode ina Li coin cell.
 9. The active electrode material of claim 1, wherein thelithium precursor comprises lithium carbonate, lithium hydroxide,lithium nitrate, lithium acetate, lithium oxalate, lithium hydride,lithium oxide, lithium peroxide, lithium sulfate, or lithium fluoride.10. The active electrode material of claim 1, wherein: the transitionmetal oxalate comprises a compound of formula[M¹ _(α)′M² _(β)′M³ _(γ)′]C₂O₄; M¹, M², and M³ are transition metals;and 0<α′≦1; 0<β′≦1; and 0<γ′≦1.
 11. The active electrode material ofclaim 10, wherein the transition metal ions comprise at least three ofNi, Co, Mn, Fe, Cr, V, Ti, Cu, Zn, Mo, W, Zr, Nb, or Ru.
 12. The activeelectrode material of claim 10, wherein M¹ is Ni; M² is Co; and M³ isMn.
 13. The active electrode material of claim 10, wherein 0<α′≦0.33;0<β′≦0.5; and 0<γ′≦0.8; and the sum of α, β, and γ is
 1. 14. The activeelectrode material of claim 1, wherein the calcining is conducted at atemperature of from about 400° C. to about 1200° C.
 15. The activeelectrode material of claim 1, wherein the lithium transition metaloxide exhibits a capacity of greater than 200 mAh/g in a Li coin cell.16. The active electrode material of claim 2, wherein the lithiumtransition metal oxide comprises a compound of formula Li_(x)[M¹ _(α)M²_(β)M³ _(γ)]O_(z); M¹, M², and M³ are transition metals; and 1<x≦2;0<α≦0.33; 0<β; 0<γ≦0.8; and 2<z≦3; and the sum of α and β is 1; and thetransition metal oxalate comprises a compound of formula[M¹ _(α′)M² _(β′)M³ _(γ′)]C₂O₄; and 0<α′≦0.33; 0<β; and 0<γ′≦0.8; andthe sum of α′ and γ′ is
 1. 17. The active electrode material of claim16, wherein the lithium precursor comprises lithium carbonate, lithiumhydroxide, lithium nitrate, lithium acetate, lithium oxalate, lithiumhydride, lithium oxide, lithium peroxide, lithium sulfate, or lithiumfluoride.
 18. An electrode comprising the active electrode material ofclaim
 1. 19. An electrochemical device comprising the electrode of claim18.